The role of esophageal longitudinal muscle in motility disorders of the esophagus is unclear. Traditional manometric techniques do not assess contraction of this muscle. The advent of a new catheter-based ultrasound probe has produced high-quality intraluminal images of the esophagus which allows for in vivo study of the esophageal longitudinal muscle. We aim to use this ultrasound probe to study patients with chest pain of noncardiac origin in an effort to further define the pathophysiologic mechanisms responsible for symptoms in these patients.